Compressor with compliant thrust bearing

ABSTRACT

A bearing housing may include a body portion, a hub, and a thrust bearing. The body portion may include a radially inwardly facing first annular surface. A structure may extend radially outward from the body portion. The hub may extend axially from the body portion and may include a radially inwardly facing second annular surface adapted to rotatably support a shaft. The thrust bearing may extend axially from the body portion and may include an outer surface, a thrust surface, an inner surface, and an undercut feature formed in one of the inner and outer surfaces. The undercut feature may define a cantilevered portion of the thrust bearing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/583,916, filed on Jan. 6, 2012. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The present disclosure relates to a compressor having a compliant thrust bearing.

BACKGROUND

This section provides background information related to the present disclosure and is not necessarily prior art.

A climate-control system such as a heat-pump system, a refrigeration system, an air conditioning system, or any other working-fluid-circulation system may include a fluid circuit having an outdoor heat exchanger, an indoor heat exchanger, an expansion device disposed between the indoor and outdoor heat exchangers, and a compressor circulating a working fluid (e.g., refrigerant or carbon dioxide) between the indoor and outdoor heat exchangers. Efficient and reliable operation of the compressor is desirable to ensure that the climate-control system in which the compressor is installed is capable of effectively and efficiently providing a cooling and/or heating effect on demand. Furthermore, reducing wear on components of the compressor may increase the longevity of the compressor and the climate-control system.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

In one form, the present disclosure provides a thrust bearing for a compressor having first and second working members. The thrust bearing may include an axially facing thrust surface, first and second surfaces, and an annular undercut feature. The thrust surface may be configured to support one of the first and second working members. The first surface may be adjacent the thrust surface. The second surface may be adjacent the thrust surface. In some embodiments, the undercut feature may be formed in only one of the first and second surfaces. The one of the first and second surfaces may include a first radially facing portion disposed axially between the thrust surface and a first axial end of the undercut feature and a second radially facing portion disposed adjacent a second axial end of the undercut feature. The second radially facing portion may be spaced apart from a drive shaft bearing.

In other embodiments, both of the first and second surfaces could include an undercut feature formed therein.

In some embodiments, the first and second surfaces could be substantially coaxial, annular surfaces.

In some embodiments, the undercut feature may be formed in the first annular surface, and the first annular surface may be disposed radially inward relative to the second annular surface.

In some embodiments, the undercut feature may include an axially extending surface that is substantially parallel to and coaxial with the first and second annular surfaces.

In some embodiments, the undercut feature may include a V-shaped cross section. In other embodiments, the undercut feature may include a U-shaped cross section.

In some embodiments, a radial depth of the undercut feature may be less than or equal to approximately one-fifth of an axial distance between said thrust surface and the undercut feature. In other embodiments, a radial depth of the undercut feature may be between approximately one-fifth and approximately two times an axial distance between said thrust surface and the undercut feature. In other embodiments, a radial depth of the undercut feature may be between approximately two times and approximately eight times an axial distance between said thrust surface and the undercut feature. In other embodiments, a radial depth of the undercut feature may be greater than or equal to approximately eight times an axial distance between said thrust surface and the undercut feature.

In some embodiments, the undercut feature may include an axial dimension of at least about 7.62 millimeters. In some embodiments, the undercut feature may include an axial dimension of approximately 2.5 millimeters or more. The axial dimension could be an axial distance between the thrust surface and an axially distal edge of the undercut feature. Alternatively, the axial dimension could be an axial distance between upper and lower edges of the undercut feature.

In another form, the present disclosure provides a bearing housing that may include a body portion, a hub, and a thrust bearing. The body portion may include a radially inwardly facing first annular surface. The hub may extend axially from the body portion and may include a radially inwardly facing second annular surface adapted to rotatably support a shaft. The thrust bearing may extend axially from the body portion and may include an outer annular surface, an axially facing thrust surface, an inner annular surface, and an undercut feature formed in one of the inner and outer annular surfaces. The undercut feature may define a cantilevered portion of the thrust bearing. The undercut feature may be directly adjacent the first annular surface.

In some embodiments, the undercut feature may be formed in the outer annular surface. In other embodiments, the undercut feature may be formed in the inner annular surface. In still other embodiments, undercut features may be formed in both of the inner and outer surfaces and may define a pair of cantilevered portions of the thrust bearing.

In some embodiments, the undercut feature may include an axially extending surface that is substantially parallel to and coaxial with the inner and outer annular surfaces.

In some embodiments, the inner annular surface of the thrust bearing and the first annular surface of the body portion may be substantially radially aligned with each other.

In some embodiments, the hub and the thrust bearing may be integrally formed with the body portion.

In yet another form, the present disclosure provides a scroll machine (e.g., a scroll compressor or a scroll expander) that may include a non-orbiting scroll, an orbiting scroll, a drive shaft, and a bearing housing. The orbiting scroll may engage the non-orbiting scroll and may be configured to orbit relative to the non-orbiting scroll. The drive shaft may drivingly engage the orbiting scroll. The bearing housing may include a body portion, a hub extending axially from the body portion, and a thrust bearing extending axially from the body portion. The hub and the thrust bearing may be integrally formed with the body portion. The hub may include a first annular surface supporting the drive shaft. The thrust bearing may include a second annular surface, a third annular surface, and a thrust surface. The thrust surface may axially support the orbiting scroll. The thrust bearing may include an annular undercut feature formed in one of the second and third annular surfaces.

In some embodiments, the body portion may include a radially inwardly facing annular surface that is directly adjacent the undercut feature.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a cross-sectional view of a compressor according to the principles of the present disclosure;

FIG. 2 is a plan view of a main bearing housing of the compressor of FIG. 1;

FIG. 3 is a cross-sectional view of the main bearing housing of FIG. 1;

FIG. 4 is a detail view of a portion of the main bearing housing identified as detail 4 in FIG. 3;

FIG. 5 is a cross-sectional view of the main bearing housing and an orbiting scroll member while the orbiting scroll member is stationary relative to the main bearing housing;

FIG. 6 is an exaggerated, schematic, partial cross-sectional view of the main bearing housing and the orbiting scroll member of FIG. 5 while the orbiting scroll member is orbiting relative to the main bearing housing;

FIG. 7 is a cross-sectional view of another main bearing housing according to the principles of the present disclosure;

FIG. 8 is a detail view of a portion of the main bearing housing identified as detail 8 in FIG. 7;

FIG. 9 is a cross-sectional view of yet another main bearing housing according to the principles of the present disclosure;

FIG. 10 is a detail view of a portion of the main bearing housing identified as detail 10 in FIG. 9;

FIG. 11 is a partial cross-sectional view of yet another main bearing housing having an undercut feature according to the principles of the present disclosure;

FIG. 12 is a partial cross-sectional view of yet another main bearing housing having another undercut feature according to the principles of the present disclosure; and

FIG. 13 is a partial cross-sectional view of yet another main bearing housing having an another undercut feature according to the principles of the present disclosure.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

With reference to FIGS. 1-6, a compressor 10 is provided that may include a hermetic shell assembly 12, a motor assembly 14, a compression mechanism 16, a first bearing-housing assembly 18, and a second bearing-housing assembly 19.

The shell assembly 12 may form a compressor housing and may include a cylindrical shell 20, an end cap 22 at an upper end thereof, a transversely extending partition 24, and a base 26 at a lower end thereof. The end cap 22 and the partition 24 may define a discharge chamber 28. The partition 24 may separate the discharge chamber 28 from a suction chamber 30. The partition 24 may include a wear ring 31 defining a discharge passage 32 extending therethrough to provide communication between the compression mechanism 16 and the discharge chamber 28. A discharge fitting 34 may be attached to shell assembly 12 at an opening 36 in the end cap 22. A discharge valve assembly 38 may be disposed within the discharge fitting 34 and may generally prevent a reverse flow condition through the discharge fitting 34. A suction inlet fitting 40 may be attached to shell assembly 12 at an opening 42.

The motor assembly 14 may include a motor stator 44, a rotor 46, and a drive shaft 48. The motor stator 44 may be press fit into the shell 20. The rotor 46 may be press fit on the drive shaft 48 and may transmit rotational power to the drive shaft 48. The drive shaft 48 may be rotatably supported by the first and second bearing-housing assemblies 18, 19. The drive shaft 48 may include an eccentric crank pin 50 having a flat 52 thereon.

The compression mechanism 16 may include an orbiting scroll 54 and a non-orbiting scroll 56. The orbiting scroll 54 may include an end plate 58 having a spiral wrap 60 on an first side thereof and an annular flat thrust surface 62 on a second side. The thrust surface 62 may interface with the first bearing-housing assembly 18, as will be subsequently described. A cylindrical hub 64 may project downwardly from the thrust surface 62. A drive bushing 66 may be received within the hub 64. The crank pin 50 of the drive shaft 48 may drivingly engage the drive bushing 66. The crank pin flat 52 may drivingly engage mating surface (not shown) of the drive bushing 66 to provide a radially compliant driving arrangement. An Oldham coupling 68 may be engaged with the orbiting and non-orbiting scrolls 54, 56 to prevent relative rotation therebetween.

The non-orbiting scroll 56 may include an end plate 70 and a spiral wrap 72 projecting downwardly from the end plate 70. The spiral wrap 72 may meshingly engage the spiral wrap 60 of the orbiting scroll 54, thereby creating a series of moving fluid pockets. The fluid pockets defined by the spiral wraps 60, 72 and end plates 58, 70 may decrease in volume as they move from a radially outer position (e.g., at a suction pressure) to a radially intermediate position (e.g., at an intermediate pressure that may be higher than the suction pressure) to a radially inner position (e.g., at a discharge pressure that may be higher than the intermediate pressure) throughout a compression cycle of the compression mechanism 16.

The end plate 70 may include a discharge passage 74 and an annular recess 76. The discharge passage 74 is in communication with at least one of the fluid pockets at the radially inner position and allows compressed working fluid (at or near the discharge pressure) to flow therethrough and into the discharge chamber 28. The annular recess 76 may at least partially receive a floating seal assembly 78 and may cooperate with the seal assembly 78 to define an axial biasing chamber 80 therebetween. The biasing chamber 80 may receive intermediate-pressure fluid from a fluid pocket in the intermediate position. A pressure differential between the intermediate-pressure fluid in the biasing chamber 80 and fluid in the suction chamber 30 exerts a net axial biasing force on the non-orbiting scroll 56 urging the non-orbiting scroll 56 toward the orbiting scroll 54 to facilitate a sealed relationship therebetween.

The first bearing-housing assembly 18 may include a bearing housing 82, a bearing 84, sleeves guides or bushings 86, and fasteners 88. The bearing housing 82 may house the bearing 84 and support the drive shaft 48 for rotational motion relative thereto. The bearing housing 82 may also support the orbiting scroll 54 for orbital motion relative thereto.

As shown in FIGS. 1-3, the bearing housing 82 may include a body 90, a plurality of legs 92, a hub 94 (FIG. 3), and a thrust bearing 96. The body 90 may be a generally annular member having an annular inner surface 98 (FIG. 3) defined by a longitudinal axis A1. The inner surface 98 may define a recess 99 in which the hub 64 of the orbiting scroll 54 may extend, as shown in FIG. 5. The legs 92 may extend radially outward from the body 90 and may engage the shell 20, as shown in FIG. 1. Each of the legs 92 may include a corresponding foot 100 having an aperture 102 adapted to threadably receive the fasteners 88 (FIG. 1). The non-orbiting scroll 56 may be secured to the feet 100 by the bushings 86 and fasteners 88.

The hub 94 may be a generally annular member including an inner surface 104 that may be coaxial with the inner surface 98 of the body 90. The hub 94 may extend axially downward (relative to the view shown in FIG. 3) from the body 90. The hub 94 may receive the bearing 84 that rotatably supports the drive shaft 48.

The thrust bearing 96 may be a generally annular member defined by the longitudinal axis A1 and extending axially upward (relative to the view shown in FIG. 3) from the body 90. As shown in FIGS. 2 and 3, the thrust bearing 96 may include a radially outer surface 106, a radially inner surface 108, and a thrust bearing surface 110. As shown in FIG. 5, the thrust bearing surface 110 may matingly engage the thrust surface 62 of the orbiting scroll 54 and may axially support the orbiting scroll 54. A film of lubricant may be present between the thrust bearing surface 110 and the thrust surface 62.

As shown in FIGS. 3 and 4, an annular groove or undercut feature 112 (FIGS. 3 and 4) may be cast, machined, and/or otherwise formed in the inner surface 108 of the thrust bearing 96 and/or in the inner surface 98 of the body 90. The undercut feature 112 may include an axially extending surface 114, an upper surface 116, and a lower surface 118. The axially extending surface 114, the upper surface 116, and the inner surface 108 may cooperate to form an annular cantilevered portion 120 of the thrust bearing 96. While not shown in FIG. 3, in some embodiments, another undercut feature could be formed in the outer surface 106 of the thrust bearing 96.

In the particular embodiment shown in FIGS. 3 and 4, the axially extending surface 114 may be radially outwardly offset from the inner surface 108 of the thrust bearing 96 by about two millimeters, for example. The upper surface 116 may be axially offset from the thrust bearing surface 110 by about four millimeters (or about 4.08 millimeters, as shown in FIG. 4), and the upper surface 116 may be axially offset from the lower surface 118 by about thirteen and one-quarter millimeters (or about 13.23 millimeters, as shown in FIG. 4). Radii between the upper surface 116 and the axially extending surface 114 and between the lower surface 118 and the axially extending surface 114 may be about one and one-half of a millimeter (1.5 millimeters), as shown in FIG. 4. Additional dimensions (expressed in millimeters) of an exemplary bearing housing 82 are shown in FIG. 3. The exemplary dimensions described above and/or shown in FIGS. 3 and 4 are provided to illustrate the scale and relative proportions of various features of a particular embodiment of the bearing housing 82. It will be appreciated that in other embodiments, one or more dimensions and/or proportions could vary from the dimensions and proportions shown in FIGS. 3 and 4.

In some embodiments, the undercut feature 112 may reduce localized stiffness of the thrust bearing 96 at or near the inner surface 108 and/or the thrust bearing surface 110, for example. This may reduce contact stress in the thrust bearing 96 at or near the inner surface 108 and/or the thrust bearing surface 110 due to axial loading of the orbiting scroll 54 onto the thrust bearing 96 during operation of the compressor 10. In some embodiments, the cantilevered portion 120 of the thrust bearing 96 may be compliant and may resiliently deflect downward in response to the orbiting scroll 54 applying a sufficiently large axial load thereon.

FIG. 6 is an exaggerated illustration of deflection of the end plate 58 of the orbiting scroll 54 that may occur while the orbiting scroll 54 orbits relative to the non-orbiting scroll 56 during operation of the compressor 10. As illustrated in FIG. 6, the end plate 58 may bow or deflect to a configuration whereby the thrust surface 62 is generally convex.

As the orbiting scroll 54 orbits about the longitudinal axis Al, a first portion 130 of the end plate 58 may exert a larger axial downward force on the thrust bearing 96 than a second portion 132 of the end plate that is angularly opposite (i.e., one-hundred-eighty degrees apart from) the first portion 130. The-areas of the end plate 58 that are defined as the first and second portions 130, 132 may change in an orbital pattern around the longitudinal axis Al relative to the thrust bearing 96.

While the orbiting scroll 54 is orbiting relative to the non-orbiting scroll 56, the end plate 58 may exert a relatively large axial force on the thrust bearing 96 at or near the first portion 130, and may exert a relatively small or no axial force at all on the thrust bearing 96 at or near the second portion 132. The reduced stiffness in the thrust bearing 96 at or near the inner surface 108 and the thrust bearing surface 110 may allow a portion of the cantilevered portion 120 corresponding to the first portion 130 to resiliently deflect downward under the relatively large axial load applied at or near the first portion 130. This may at least locally reduce stress in the thrust bearing 96 and reduce wear on the thrust bearing surface 110 and/or on the thrust surface 62 of the orbiting scroll 54.

With reference to FIGS. 7 and 8, another bearing housing 182 will be described. The structure and function of the bearing housing 182 may be generally similar to that of the bearing housing 82 described above apart from any exceptions noted below and/or shown in the figures. Therefore, similar features may not be described again in detail. The bearing housing 182 could be incorporated into the compressor 10 in place of the bearing housing 82.

The bearing housing 182 may include a body 190, a plurality of legs 192, a hub 194, and a thrust bearing 196. The body 190 may be a generally annular member having an annular inner surface 198 defined by a longitudinal axis A2. The thrust bearing 196 may be a generally annular member defined by the longitudinal axis A2 and extending axially upward (relative to the view shown in FIG. 7) from the body 190. The thrust bearing 196 may include a radially outer surface 206, a radially inner surface 208, and a thrust bearing surface 210.

A first annular groove or undercut feature 212 may be cast, machined, and/or otherwise formed in the inner surface 208 of the thrust bearing 196 and/or in the inner surface 198 of the body 190. The first undercut feature 212 may include an axially extending surface 214, an upper surface 216, and a lower surface 218. The axially extending surface 214, the upper surface 216, and the inner surface 208 may cooperate to form a first annular cantilevered portion 220 of the thrust bearing 196.

A second annular groove or undercut feature 222 may be cast, machined, or otherwise formed in the outer surface 206 of the thrust bearing 196. The second undercut feature 222 may include an axially extending surface 224, an upper surface 226, and a lower surface 228. The axially extending surface 224, the upper surface 226, and the outer surface 206 may cooperate to form a second annular cantilevered portion 230 of the thrust bearing 196.

The first and second undercut features 212, 222 may reduce localized stiffness of the thrust bearing 196 at or near the outer surface 206, the inner surface 208, and/or the thrust bearing surface 210, for example. This may reduce at least local contact stress in the thrust bearing 196 at or near the outer surface 206, the inner surface 208, and/or the thrust bearing surface 210 due to axial loading of the orbiting scroll 54 onto the thrust bearing 196 during operation of the compressor 10. In some embodiments, one or both of the first and second cantilevered portions 220, 230 of the thrust bearing 196 may be compliant and resiliently deflect downward in response to the orbiting scroll 54 applying a sufficiently large axial load thereon.

FIGS. 7 and 8 illustrate dimensions (in millimeters) of an exemplary embodiment of the bearing housing 182. The exemplary dimensions are provided to illustrate the scale and relative proportions of various features of a particular embodiment of the bearing housing 182. It will be appreciated that in other embodiments, one or more dimensions and/or proportions could vary from the dimensions and proportions shown in FIGS. 7 and 8. For example, in some embodiments, an axial dimension of either or both of the first and second undercut features 212, 222 may include an axial dimension of at least about 7.62 millimeters. Although, in other embodiments, either or both of the first and second undercut features 212, 222 may include an axial dimension of less than 7.62 millimeters.

With reference to FIGS. 9 and 10, another bearing housing 282 will be described. The structure and function of the bearing housing 282 may be substantially identical to that of the bearing housing 182 described above apart from any exceptions noted below and/or shown in the figures. Therefore, similar features may not be described again in detail. The bearing housing 282 could be incorporated into the compressor 10 in place of the bearing housing 82, 182.

Like the bearing housing 182, the bearing housing 282 may include a thrust bearing 296 that extends axially upward (relative to the view shown in FIG. 9) from a body 290. The thrust bearing 296 may include a radially outer surface 306, a radially inner surface 308, and a thrust bearing surface 310. A first annular groove or undercut feature 312 may be formed in the inner surface 308 of the thrust bearing 296 and/or in an inner surface 298 of the body 290. A second annular groove or undercut feature 322 may be formed in the outer surface 306 of the thrust bearing 296.

FIGS. 9 and 10 illustrate dimensions (in millimeters) of an exemplary embodiment of the bearing housing 282. The exemplary dimensions are provided to illustrate the scale and relative proportions of various features of a particular embodiment of the bearing housing 282. It will be appreciated that in other embodiments, one or more dimensions and/or proportions could vary from the dimensions and proportions shown in FIGS. 9 and 10.

With reference to FIG. 11, another thrust bearing 496 will be described. The structure and function of the thrust bearing 496 may be substantially similar to that of any of the thrust bearings 96, 196, 296 described above apart from any exceptions noted below and/or shown in the figures. Therefore, similar features may not be described again in detail. The thrust bearing 496 could be incorporated into any of the bearing housings 82, 182, 282 described above, for example.

The thrust bearing 496 may include an annular surface 507 and a thrust bearing surface 510. The annular surface 507 shown in FIG. 11 could be either a radially inner surface (e.g., similar to the inner surfaces 108, 208, 308) or a radially outer surface (e.g., similar to the outer surfaces 106, 206, 306). An undercut feature 512 may be formed in the annular surface 507. The undercut feature 512 may be generally V-shaped and may include an upper surface 516, a lower surface 518, and an apex 520. An angle between the upper and lower surfaces 516, 518 may be less than or equal to ninety degrees. The undercut feature 512 may form a cantilevered portion 530 of the thrust bearing 496. In some embodiments, a radial depth of the apex 520 relative to the annular surface 507 may be substantially greater than an axial distance between an upper end 517 of the upper surface 516 and the thrust bearing surface 510. This may further reduce at least local stiffness in the thrust bearing 496 and may facilitate additional compliance or resilient deflection of the cantilevered portion 530.

It will be appreciated that in some embodiments, the specific shape and proportions of the undercut feature 512 may differ from that described above. For example, in some embodiments, the undercut feature 512 could be asymmetrical. That is, one of the upper and lower surfaces 516, 518 may be angled more or less than the other of the upper and lower surfaces 516, 518 relative to the longitudinal axis A1, A2, A3 of the bearing housing 82, 182, 282. In some embodiments, the lower surface 518 could be substantially parallel to the longitudinal axis A1, A2, A3. Additionally or alternatively, one of the upper and lower surfaces 516, 518 may be longer or shorter than the other of the upper and lower surfaces 516, 518.

With reference to FIG. 12, another thrust bearing 596 will be described. The structure and function of the thrust bearing 596 may be substantially similar to that of any of the thrust bearings 96, 196, 296, 496 described above apart from any exceptions noted below and/or shown in the figures. Therefore, similar features may not be described again in detail. The thrust bearing 596 could be incorporated into any of the bearing housings 82, 182, 282 described above, for example.

The thrust bearing 596 may include an annular surface 607 and a thrust bearing surface 610. The annular surface 607 shown in FIG. 12 could be either a radially inner surface (e.g., similar to the inner surfaces 108, 208, 308) or a radially outer surface (e.g., similar to the outer surfaces 106, 206, 306). An undercut feature 612 may be formed in the annular surface 607. The undercut feature 612 may be generally V-shaped and may include an upper surface 616, a lower surface 618, and an apex 620. An angle between the upper and lower surfaces 616, 618 may be greater than or equal to ninety degrees. The undercut feature 612 may form a cantilevered portion 630 of the thrust bearing 596. A radial depth of the undercut feature 612 may be substantially more shallow than the radial depth of the undercut feature 512 shown in FIG. 11.

With reference to FIG. 13, another thrust bearing 696 will be described. The structure and function of the thrust bearing 696 may be substantially similar to that of any of the thrust bearings 96, 196, 296, 496, 596 described above apart from any exceptions noted below and/or shown in the figures. Therefore, similar features may not be described again in detail. The thrust bearing 696 could be incorporated into any of the bearing housings 82, 182, 282 described above, for example.

The thrust bearing 696 may include an annular surface 707 and a thrust bearing surface 710. The annular surface 707 shown in FIG. 13 could be either a radially inner surface (e.g., similar to the inner surfaces 108, 208, 308) or a radially outer surface (e.g., similar to the outer surfaces 106, 206, 306). An undercut feature 712 may be formed in the annular surface 707. The undercut feature 712 may include an upper surface 716, a lower surface 718, and an axially extending surface 720. The undercut feature 712 can be generally U-shaped. The upper and lower surfaces 716, 718 may be substantially parallel to each other and the thrust bearing surface 710 and may be substantially perpendicular to the axially extending surface 720. The undercut feature 712 may form a cantilevered portion 730 of the thrust bearing 696. In some embodiments, a radial depth of the axially extending surface 720 relative to the annular surface 707 may be approximately equal to an axial distance between the upper surface 716 and the thrust bearing surface 710. In other embodiments, the radial depth of the axially extending surface 720 relative to the annular surface 707 may be less than or greater than the axial distance between the upper surface 716 and the thrust bearing surface 710.

It will be appreciated that in some embodiments, the specific shape and proportions of the undercut feature 712 may differ from that described above. For example, in some embodiments, the undercut feature 712 could be formed such that the surface 720 has a curved or semicircular cross-sectional profile. In some embodiments, an entire cross-sectional profile of the undercut feature 712 could be curved or semicircular. In some embodiments, the upper and/or lower surfaces 716, 718 could be angled relative to the longitudinal axis A1, A2, A3.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. For example, the sizes, proportions, shapes, and/or configurations of the thrust bearings 96, 196, 296, 496, 596, 696 and/or the undercut features 112, 212, 222, 312, 322, 520, 620, 720 described above could be modified or varied from the sizes, proportions, shapes, and/or configurations described above and/or shown in the figures to suit a given application. Furthermore, individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such modifications and variations are not to be regarded as a departure from the disclosure, and all such modifications and variations are intended to be included within the scope of the disclosure. 

What is claimed is:
 1. A thrust bearing for a compressor having first and second working members, the thrust bearing comprising: an axially facing thrust surface configured to support one of the first and second working members; a first surface adjacent said thrust surface; a second surface adjacent said thrust surface; an annular undercut feature formed in only one of said first and second surfaces, said one of said first and second surfaces including a first radially facing portion disposed axially between said thrust surface and a first axial end of said undercut feature and a second radially facing portion disposed adjacent a second axial end of said undercut feature, said second radially facing portion being spaced apart from a drive shaft bearing.
 2. The thrust bearing of claim 1, wherein said first and second surfaces are annular surfaces.
 3. The thrust bearing of claim 1, wherein said undercut feature is formed in said first surface, and wherein said first surface is disposed radially inward relative to said second surface.
 4. The thrust bearing of claim 1, wherein said undercut feature includes an axially extending surface that is substantially parallel to and coaxial with said first and second surfaces.
 5. The thrust bearing of claim 1, wherein said undercut feature includes a V-shaped cross section.
 6. The thrust bearing of claim 1, wherein said undercut feature includes a U-shaped cross section.
 7. The thrust bearing of claim 1, wherein a radial depth of said undercut feature is less than or equal to approximately one-fifth an axial distance between said thrust surface and said undercut feature.
 8. The thrust bearing of claim 1, wherein a radial depth of said undercut feature is between approximately one-fifth and approximately two times an axial distance between said thrust surface and said undercut feature.
 9. The thrust bearing of claim 1, wherein a radial depth of said undercut feature is between approximately two times and approximately eight times an axial distance between said thrust surface and said undercut feature.
 10. The thrust bearing of claim 1, wherein a radial depth of said undercut feature is more than or equal to approximately eight times an axial distance between said thrust surface and said undercut feature.
 11. The thrust bearing of claim 1, wherein said undercut feature includes an axial dimension of at least approximately 2.5 millimeters.
 12. A bearing housing comprising: a body portion including a radially inwardly facing first annular surface; a hub extending axially from said body portion and including a radially inwardly facing second annular surface adapted to rotatably support a shaft; a thrust bearing extending axially from said body portion and including an outer surface, an inner surface, a thrust surface between said outer and inner surfaces, and an undercut feature formed in one of said outer and inner surfaces, said undercut feature defining a cantilevered portion of said thrust bearing, said undercut feature being directly adjacent said first annular surface.
 13. The bearing housing of claim 12, wherein said undercut feature is formed in said outer surface.
 14. The bearing housing of claim 12, wherein said undercut feature is formed in said inner surface.
 15. The bearing housing of claim 14, further comprising another undercut feature formed in said outer surface and defining another cantilevered portion of said thrust bearing.
 16. The bearing housing of claim 12, wherein said outer and inner surfaces are annular surfaces, and said thrust surface is an axially facing surface.
 17. The bearing housing of claim 12, wherein said inner surface of said thrust bearing and said first annular surface of said body portion are substantially radially aligned with each other.
 18. The bearing housing of claim 12, wherein a radial depth of said undercut feature is less than or equal to approximately one-fifth an axial distance between said thrust surface and said undercut feature.
 19. The bearing housing of claim 12, wherein a radial depth of said undercut feature is between approximately one-fifth and approximately two times an axial distance between said thrust surface and said undercut feature.
 20. The bearing housing of claim 12, wherein a radial depth of said undercut feature is between approximately two times and approximately eight times an axial distance between said thrust surface and said undercut feature.
 21. The bearing housing of claim 12, wherein a radial depth of said undercut feature is greater than or equal to approximately eight times an axial distance between said thrust surface and said undercut feature.
 22. The bearing housing of claim 12, wherein said hub and said thrust bearing are integrally formed with said body portion.
 23. A scroll machine comprising: a non-orbiting scroll; an orbiting scroll engaging said non-orbiting scroll and configured to orbit relative to said non-orbiting scroll; a drive shaft drivingly engaging said orbiting scroll; a bearing housing including a body portion, a hub extending axially from said body portion, and a thrust bearing extending axially from said body portion, said hub and said thrust bearing being integrally formed with said body portion, said hub including a first annular surface supporting said drive shaft, said thrust bearing including a second annular surface, a third annular surface, and a thrust surface, said thrust surface axially supporting said orbiting scroll, said thrust bearing including an annular undercut feature formed in one of said second and third annular surfaces.
 24. The scroll machine of claim 23, wherein said second annular surface is disposed radially inward relative to said third annular surface, and wherein said second annular surface includes said undercut feature, but said third annular surface does not include an annular undercut feature.
 25. The scroll machine of claim 23, wherein said one of the second and third annular surfaces is substantially radially aligned with an inner annular surface of said body portion.
 26. The scroll machine of claim 23, wherein said body portion includes a radially inwardly facing annular surface that is directly adjacent said undercut feature. 